Classifications

• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
  • C12P21/00—Preparation of peptides or proteins
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07K—PEPTIDES
  • C07K16/00—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies
  • C07K16/18—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans
  • C07K16/28—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants
  • C07K16/2803—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants against the immunoglobulin superfamily
  • C07K16/2812—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants against the immunoglobulin superfamily against CD4
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K39/00—Medicinal preparations containing antigens or antibodies
  • A61K39/395—Antibodies; Immunoglobulins; Immune serum, e.g. antilymphocytic serum
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P37/00—Drugs for immunological or allergic disorders
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
  • C12N15/00—Mutation or genetic engineering; DNA or RNA concerning genetic engineering, vectors, e.g. plasmids, or their isolation, preparation or purification; Use of hosts therefor
  • C12N15/09—Recombinant DNA-technology
  • C12N15/11—DNA or RNA fragments; Modified forms thereof; Non-coding nucleic acids having a biological activity
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K38/00—Medicinal preparations containing peptides
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07K—PEPTIDES
  • C07K2317/00—Immunoglobulins specific features
  • C07K2317/20—Immunoglobulins specific features characterized by taxonomic origin
  • C07K2317/24—Immunoglobulins specific features characterized by taxonomic origin containing regions, domains or residues from different species, e.g. chimeric, humanized or veneered
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07K—PEPTIDES
  • C07K2319/00—Fusion polypeptide

Definitions

• the present invention relates to altered antibodies and their preparation.
• the invention is typically applicable to the production of humanised antibodies.
• Antibodies typically comprise two heavy chains linked together by disulphide bonds and two light chains. Each light chain is linked to a respective heavy chain by disulphide bonds. Each heavy chain has at one end a variable domain followed by a number of constant domains. Each light chain has a variable domain at one end and a constant domain at its other end. The light chain variable domain is aligned with the variable domain of the heavy chain.
• the light chain constant domain is aligned with the first constant domain of the heavy chain. The constant domains in the light and heavy chains are not involved directly in binding the antibody to antigen.
• variable domains of each pair of light and heavy chains form the antigen binding site.
• the domains on the light and heavy chains have the same general structure and each domain comprises a framework of four regions, whose sequences are relatively conserved, connected by three complementarity determining regions (CDRs) .
• the four framework regions largely adopt a beta-sheet conformation and the CDRs form loops connecting, and in some cases forming part of, the beta-sheet structure.
• the CDRs are held in close proximity by the framework regions and, with the CDRs from the other domain, contribute to the formation of the antigen binding site.
• the preparation of an altered antibody in which the CDRs are derived from a different species than the framework of the antibody's variable domains is disclosed in EP-A-0239400.
• the CDRs may be derived from a rat or mouse monoclonal antibody.
• the framework of the variable domains, and the constant domains, of the altered antibody may be derived from a human antibody.
• Humanised CAMPATH-1 antibody is disclosed in EP-A-0328404. We have now devised a new way of preparing an altered antibody.
• the present invention provides a process for the preparation of an antibody chain in which the CDRs of the variable domain of the antibody chain are derived from a first mammalian species and the framework of the variable domain and, if present, the or each constant domain of the antibody chain are derived from a second different mammalian species, which process comprises: (i) mutating the framework-encoding regions of DNA encoding a variable domain of an antibody chain of the said first species such that the mutated framework-encoding regions encode the said framework derived from the said second species; and
• step (ii) expressing the said antibody chain utilising the mutated DNA from step (i) .
• variable domain of either or both chains of an antibody can therefore be altered by:
• step (c) mutating the framework-encoding regions of DNA encoding the said variable domain such that the mutated framework-encoding regions encode the framework determined upon in step (b) ;
• step (d) linking the mutated DNA obtained in step (c) to DNA encoding a constant domain of the said second species and cloning the DNA into an expression vector;
• the antibody chain may be co-expressed with a complementary antibody chain. At least the framework of the variable domain and the or each constant domain of the complementary chain generally are derived from the said second species also. A light chain and a heavy chain may be co-expressed. Either or both chains may have been prepared by the process of the invention. Preferably the CDRs of both chains are derived from the same selected antibody. An antibody comprising both expressed chains can be recovered.
• the antibody preferably has the structure of a natural antibody or a fragment thereof.
• the antibody may therefore comprise a complete antibody, a (Fab')2 fragment, a Fab fragment, a light chain dimer or a heavy chain.
• the antibody may be an IgG such as an igGl, IgG2, IgG3 or IgG4 IgM, IgA, IgE or IgD.
• the antibody may be a chimaeric antibody of the type described in WO 86/01533.
• a chimaeric antibody according to WO 86/01533 comprises an antigen binding region and a non-immunoglobulin region.
• the antigen binding region is an antibody light chain variable domain or heavy chain variable domain.
• the chimaeric antibody comprises both light and heavy chain variable domains.
• the non-immunoglobulin region is fused at its C-terminus to the antigen binding region.
• the non- immunoglobulin region is typically a non-immunoglobulin protein and may be an enzyme region, a region derived from a protein having known binding specificity, from a protein toxin or indeed from any protein expressed by a gene.
• the two regions of the chimaeric antibody may be connected via a cleavable linker sequence.
• the invention is preferably employed to humanise an antibody, typically a monoclonal antibody and, for example, a rat or mouse antibody.
• the framework and constant domains of the resulting antibody are therefore human framework and constant domains whilst the CDRs of the light and/or heavy chain of the antibody are rat or mouse CDRs.
• Preferably all CDRs are rat or mouse CDRs.
• the antibody may be a human IgG such as IgGl, IgG2, IgG3, IgG4; IgM; IgA; IgE or IgD carrying rat or mouse CDRs.
• the process of the invention is carried out in such a way that the resulting antibody retains the antigen binding capability of the antibody from which it is derived.
• An antibody is reshaped according to the invention by mutating the framework-encoding regions of DNA coding for the variable domains of the antibody. This antibody and the reshaped antibody should both be capable of binding to the same antigen.
• the starting antibody is typically an antibody of a selected specificity.
• the variable domain framework of the antibody is preferably reshaped to about the closest variable domain framework of an antibody of another species.
• about the closest is meant about the most homologous in terms of amino acid sequences.
• Step 1 Determining the nucleotide and predicted amino acid sequence of the antibody light and heavy chain variable domains To reshape an antibody only the amino acid sequence of antibody's heavy and light chain variable domains needs to be known. The sequence of the constant domains is irrelevant because these do not contribute to the reshaping strategy.
• the simplest method of determining an antibody's variable domain amino acid sequence is from cloned cDNA encoding the heavy and light chain variable domain. There are two general methods for cloning a given antibody's heavy and light chain variable domain cDNAs: (1) via a conventional cDNA library, or (2) via the polymerase chain reaction (PCR) . Both of these methods are widely known. Given the nucleotide sequence of the cDNAs, it is a simple matter to translate this information into the predicted amino acid sequence of the antibody variable domains.
• Step 2 Designing the reshaped antibody
• a given antibody's antigen specificity and affinity is primarily determined by the amino acid sequence of the variable region CDRs.
• Variable domain framework residues have little or no direct contribution.
• the primary function of the framework regions is to hold the CDRs in their proper spacial orientation to recognize antigen.
• substitution of rodent CDRs into a human variable domain framework is most likely to result in retention of their correct spacial orientation if the human variable domain is highly homologous to the rodent variable domain from which they originated.
• a human variable domain should preferably be chosen therefore that is highly homologous to the rodent variable domain(s) .
• a suitable human antibody variable domain sequence can be selected as follows:
• the second benefit is that, by restricting analyses to only human immunoglobulin sequences, the output will not be cluttered by the presence of rodent immunoglobulin sequences.
• rodent immunoglobulin sequences There are far more rodent immunoglobulin sequences in databases than there are human.
• the actual reshaped antibody (the end result) should contain CDRs derived from the rodent antibody and a variable domain framework from the human antibody chosen above.
• Step 3 The actual reshaping methodolo ⁇ ies/technicrues
• a cDNA encoding the desired reshaped antibody is preferably made beginning with the rodent cDNA from which the rodent antibody variable domain sequence(s) was originally determined.
• the rodent variable domain amino acid sequence is compared to that of the chosen human antibody variable domain sequence.
• the residues in the rodent variable domain framework are marked that need to be changed to the corresponding residue in the human to make the rodent framework identical to that of the human framework. There may also be residues that need adding to or deleting from the rodent framework sequence to make it identical to that of the human.
• Oligonucleotides are synthesised that can be used to mutagenize the rodent variable domain framework to contain the desired residues. Those oligonucleotides can be of any convenient size. One is normally only limited in length by the capabilities of the particular synthesizer one has available. The method of oligonucleotide-directed in vitro mutagenesis is well known.
• this method of reshaping as opposed to splicing CDRs into a human framework are that (1) this method does not require a pre-existing cDNA encoding the human framework to which to reshape and (2) splicing CDRs is technically more difficult because there is usually a large region of poor homology between the mutagenic oligo- nucleotide and the human antibody variable domain. This is not so much a problem with the method of splicing human framework residues onto a rodent variable domain because there is no need for a pre-existing cDNA encoding the human variable domain. The method starts instead with the rodent cDNA sequence.
• splicing framework regions is technically easier because there is a high degree of homology between the mutagenic oligonucleotide and the rodent variable domain framework. This is true because a human antibody variable domain framework has been selected that is most homologous to that of the rodent.
• Step 4 The transfection and expression of the reshaped antibody Following the mutagenesis reactions to reshape the antibody, the cDNAs are linked to the appropriate DNA encoding light or heavy chain constant region, cloned into an expression vector, and transfected into mammalian cells. These steps can be carried out in routine fashion.
• a reshaped antibody may therefore be prepared by a process comprising: a) preparing a first replicable expression vector including a suitable promoter operably linked to a DNA sequence which encodes at least a variable domain of an Ig heavy or light chain, the variable domain comprising framework regions from a first antibody and CDRs comprising at least parts of the CDRs from a second antibody of different specificity; b) if necessary, preparing a second replicable expression vector including a suitable promoter operably linked to a DNA sequence which encodes at least the variable domain of a complementary Ig light or heavy chain respectively; c) transforming a cell line with the first or both prepared vectors; and d) culturing said transformed cell line to produce said altered antibody.
• the DNA sequence in step a) encodes both the variable domain and the or each constant domain of the antibody chain, the or each constant domain being derived from the first antibody.
• the antibody can be recovered and purified.
• the cell line which is transformed to produce the altered antibody may be a Chinese Hamster Ovary (CHO) cell line or an immortalised mammalian cell line, which is advantageously of lymphoid origin, such as a myeloma, hybridoma, trioma or quadroma cell line.
• the cell line may also comprise a normal lymphoid cell, such as a B-cell, which has been immortalised by transformation with a virus, such as the Epstein-Barr virus.
• the immortalised cell line is a myeloma cell line or a derivative thereof.
• the cell line used to produce the altered antibody is preferably a mammalian cell line, any other suitable cell line, such as a bacterial cell line or a yeast cell line, may alternatively be used.
• E___ coli - derived bacterial strains could be used.
• step (b) may be carried out by further manipulating the vector produced in step (a) so that this vector encodes not only the variable domain of an altered antibody light or heavy chain, but also the complementary variable domain.
• step (b) is carried out by preparing a second vector which is used to transform the immortalised cell line.
• This alternative leads to easier construct preparation, but may be less preferred than the first alternative in that it may not lead to as efficient production of antibody.
• the transformed cell line may be produced for example by transforming a suitable bacterial cell with the vector and then fusing the bacterial cell with the immortalised cell line by spheroplast fusion.
• the DNA may be directly introduced into the immortalised cell line by electroporation or other suitable method.
• An antibody is consequently produced in which CDRs of a variable domain of an antibody chain are homologous with the corresponding CDRs of an antibody of a first mammalian species and in which the framework of the variable domain and the constant domains of the antibody are homologous with the corresponding framework and constant domains of an antibody of a second, different, mammalian species.
• all three CDRs of the variable domain of a light or heavy chain are derived from the first species.
• the present process has been applied to obtain an antibody against human CD4 antigen. Accordingly, the invention also provides an antibody which is capable of binding to human CD4 antigen, in which the CDRs of the light chain of the antibody have the amino acid sequences:
• CDR3 QQYNNYPWT, in which the CDRs of the heavy chain of the antibody have the amino acid sequences:
• CDR1 NYGMA
• CDR2 TISHDGSDTYFRDSVKG
• the antibody preferably has the structure of a natural antibody or a fragment thereof.
• the antibody may therefore comprise a complete antibody, a (Fab') 2 fragment, a Fab fragment, _ a light chain dimer or a heavy chain.
• the antibody may be an IgG such as IgGl, IgG2, IgG3 or IgG4 IgM, IgA, IgE or IgD.
• the antibody may be a chimaeric antibody of the type described in WO 86/01533.
• a chimaeric antibody according to WO 86/01533 comprises an antigen binding region and a non-immunoglobulin region.
• the antigen binding region is an antibody light chain variable domain or heavy chain variable domain.
• the chimaeric antibody comprises both light and heavy chain variable domains.
• the non-immunoglobulin region is fused at its C-terminus to the antigen binding region.
• the non- immunoglobulin region is typically a non-immunoglobulin protein and may be an enzyme region, a region derived from a protein having known binding specificity, from a protein toxin or indeed from any protein expressed by a gene.
• the two regions of the chimaeric antibody may be connected via a cleavable linker sequence.
• the invention is preferably employed to humanise a CD4 antibody such as a rat or mouse CD4 antibody.
• the framework and the constant domains of the resulting antibody are therefore human framework and constant domains whilst the CDRs of the light and/or heavy chain of the antibody are rat or mouse CDRs.
• Preferably all CDRs are rat or mouse CDRs.
• the antibody may be a human IgG such as IgGl, IgG2, IgG3, IgG4; IgM; IgA; IgE or IgD carrying rat or mouse CDRs.
• the framework of the antibody heavy chain is homologous to the corresponding framework of the human antibody KOL (Schmidt et al, Hoppe-Seyler's Z. Physiol. Chem., 3_£4 713-747, 1983).
• the sixth residue of framework 4 in this case is suitably Thr or Pro, preferably Thr.
• This residue is the 121st residue in the KOL antibody heavy chain variable region (Schmidt et al. 1983) , and is identified as residue 108 by Kabat (Kabat et al. "Sequences of proteins of immunological interest", US Dept of Health and Human Services, US Government Printing Office, 1987) .
• the framework of the antibody heavy chain is homologous to the corresponding framework of the human antibody NEW (Saul et al, J. Biol.Chem. 253: 585-597, 1978) .
• the final residue of framework 1 in this case is suitably Ser or Thr, preferably Ser. This residue is at position 30 (Kabat et al. 1987) .
• the framework of the antibody light chain is homologous to the variable domain framework of the protein REI (Epp et al, Eur. J. Biochem., _5 , 513-524, 1974).
• the framework regions of one or both chains of a CD4 antibody can be reshaped by the present process.
• one or both chains of a CD4 antibody may be reshaped by the procedure described in EP-A-0239400.
• the procedure of EP-A-0239400 involves replacing CDRs rather than the replacement of frameworks.
• the CDRs are grafted onto a framework derived from a mammalian non-rat species, typically a human. This may be achieved by oligonucleotide-directed in vitro utagenesis of the CDR- encoding regions of an antibody chain, light or heavy, from a mammalian non-rat species.
• the oligonucleotides in such an instance are selected so that the resulting CDR-grafted antibody has the light chain CDRs 1 to 3 and the heavy chain CDRs 1 to 3 shown above.
• the reshaped CD4 antibody can be used to induce tolerance to an antigen. It can be used to alleviate autoimmune diseases such as rheumatoid arthritis. It can be used to prevent graft rejection. Tolerance to a graft such as an organ graft or a bone marrow transplantation can be achieved. Also, the reshaped CD4 antibody might be used to alleviate allergies. Tolerance to allergens could be achieved.
• the CD4 antibody may be depleting or non-depleting.
• a depleting antibody is an antibody which depletes more than 50%, for example from 90 to 99%, of target cells in vivo.
• a non-depleting antibody depletes fewer than 50%, for example, from 10 to 25% and preferably less than 10% of target cells in vivo.
• a CD4 antibody may be administered alone or may be co-administered with a non-depleting or depleting CD8 antibody.
• the CD4 antibody, depleting or non-depleting, and CD8 monoclonal antibody, depleting or non-depleting may be administered sequentially in any order or may be administered simultaneously.
• An additional antibody, drug or protein may be administered before, during or after administration of the antibodies.
• a CD4 antibody and, indeed, a CD8 antibody as appropriate are given parenterally, for example intravenously.
• the antibody may be administered by injection or by infusion.
• the antibody is formulated in a pharmaceutical composition further comprising a pharmaceutically acceptable carrier or diluent. Any appropriate carrier or diluent may be employed, for example phosphate-buffered saline solution.
• a pharmaceutically acceptable carrier or diluent may be employed, for example phosphate-buffered saline solution.
• the amount of non-depleting or depleting CD4 and, if desired, CD8 antibody administered to a patient depends upon a variety of factors including the age and weight of a patient, the condition which is being treated and the antigen(s) to which it is desired to induce tolerance.
• a mAb In a model mouse system from l ⁇ g to 2mg, preferably from 400 ⁇ g to lmg, of a mAb is administered at any one time. In humans from 3 to 500mg, for example from 5 to 200mg, of antibody may be administered at any one time. Many such doses may be given over a period of several weeks, typically 3 weeks.
• a foreign antigen(s) to which it is desired to induce tolerance can be administered to a host before, during, or after a course of CD4 antibody (depleting or non-depleting) and/or CD8 antibody (depleting or non-depleting) .
• the antigen(s) is administered one week after commencement of antibody administration, and is terminated three weeks before the last antibody administration.
• Tolerance can therefore be induced to an antigen in a host by administering non-depleting or depleting CD4 and CD8 mAbs and, under cover of the mAbs, the antigen.
• a patient may be operated on surgically under cover of the non-depleting or depleting CD4 and CD8 mAbs to be given a tissue transplant such as an organ graft or a bone marrow transplant.
• tolerance may be induced to an antigen already possessed by a subject. Long term specific tolerance can be induced to a self antigen or antigens in order to treat autoimmune disease such as multiple sclerosis or rheumatoid arthritis. The condition of a patient suffering from autoimmune disease can therefore be alleviated.
• Figure 1 shows the nucleotide and predicted amino acid sequence of rat CD4 antibody light chain variable region. The number of the first and last amino acid or nucleotide in each line is indicated in the left and right margins, respectively.
• Base pairs 1-269 Hindlll-PvuII
• 577-620 [BglII/BclI3-BamHI) are part of the vector M13V K PCR3, while base pairs 270-576 are from the PCR product of the CD4 antibody light chain variable region (V L ) .
• CDRs boxes were identified by comparison to known immunological sequences (Kabat et ai, "Sequences of proteins of immunological interest, US Dept of Health and Human Services, US Government Printing Office, 1987) .
• Figure 2 shows the nucleotide and predicted amino acid sequence of the reshaped CAMPATH-1 antibody light chain cDNA. The number of the first and last amino acid or nucleotide in each line is indicated in the left and right margins, respectively. CDRs are identified by boxes.
• Figure 3 shows the nucleotide and predicted amino acid sequence of the reshaped CD4 antibody light chain cDNA CD4VLREI. The number of the first and last amino acid or nucleotide in each line is indicated in the left and right margins, respectively. CDRs are identified by boxes.
• Figure 4 shows the nucleotide and predicted amino acid sequence of rat CD4 antibody heavy chain variable region. The number of the first and last amino acid or nucleotide in each line is indicated in the left and right margins, respectively. CDRs are identified by boxes. Base pairs 1- 272 (Hindlll-Pstl) and 603-817 (BstEII-BamHI) are part of the vector M13V H PCR1, while base pairs 273-602 are from the PCR product of the CD4 antibody heavy chain variable region
• FIG. 5 shows the nucleotide and predicted amino acid sequence of the reshaped CAMPATH-1 antibody heavy chain cDNA. The number of the first and last amino acid or nucleotide in each line is indicated in the left and right margins, respectively. CDRs are identified by boxes.
• Figure 6 shows the nucleotide and predicted amino acid sequence of the reshaped CD4 antibody heavy chain cDNA
• CD4VjjNEW-Thr 30 The number of the first and last amino acid or nucleotide in each line is indicated in the left and right margins, respectively. CDRs are identified by boxes.
• Figure 7 shows the nucleotide and predicted amino acid sequence of the reshaped CD4 antibody heavy chain cDNA CD4V H NEW-Ser 3 °. The number of the first and last amino acid or nucleotide in each line is indicated in the left and right margins, respectively. CDRs are identified by boxes.
• Figure 8 shows the heavy chain variable (V) region amino acid sequence of the human myeloma protein KOL. CDRs are identified by boxes. This sequence is taken from the Swiss-Prot protein sequence database.
• Figure 9 shows the nucleotide and predicted amino acid sequence of the reshaped CD4 antibody heavy chain V region CD4V H KOL-Pro 113 . The number of the first and last amino acid or nucleotide in each line is indicated in the left and right margins, respectively. CDRs are identified by boxes.
• Figure 10 shows the nucleotide and predicted amino acid sequence of the reshaped CD4 antibody heavy chain V region CD4V H KOL-Pro 113 without immunoglobulin promoter. The number of the first and last amino acid or nucleotide in each line is indicated in the left and right margins, respectively. CDRs are identified by boxes.
• Figure 11 shows the nucleotide and predicted amino acid sequence of the reshaped CD4 antibody heavy chain V region CD4V jj KOL-Thr 113 .
• the number of the first and last amino acid or nucleotide in each line is indicated in the left and right margins, respectively.
• CDRs are identified by boxes.
• Figure 12 shows the nucleotide and predicted amino acid sequence of the reshaped CD4 antibody heavy chain V region CD4V jj KOL-Thr 113 without immunoglobulin promoter. The number of the first and last amino acid or nucleotide in each line is indicated in the left and right margins, respectively. CDRs are identified by boxes.
• Figure 13 shows the results of an ELISA that compares the avidity of YNB46.1.8 and CD4V H KOL-Thr 113 antibodies. The X-axis indicates the concentration ( ⁇ g/ml) of YNB46.1.8 (triangles) or CD4V H KOL-Thr 113 (circles) antibody. The Y- axis indicates the optical density at 492 nanometers.
• the rat-derived anti- human CD4 antibody clone YNB46.1.8 (IgG2 D , kappa light chain serotype) , was the result of fusion between a rat splenocyte and the Lou strain rat myeloma cell line Y3-Ag 1.2.3 (Galfre et ai. Nature, 277: 131-133, 1979) and was selected by its binding to a rat T cell line NB2-6TG stably transfected with an expression vector containing a complementary DNA (cDNA) encoding the human CD4 antigen (Madden et al. Cell, 42.: 93-104, 1985).
• Antibody was purified by high pressure liquid chromatography (HPLC) .
• Poly(A) + RNA was heated at 70*C for 5 minutes and cooled on ice just prior to use.
• a 25 ⁇ l first strand synthesis reaction consisted of 5 ⁇ g poly(A) + RNA, 250 ⁇ M each dNTP, 50 mM Tris.HCl (pH 8.2 at 42*C), 10 mM MgCl 2 , 100 mM KCl, 10 mM dithiothreitol, 23 units reverse transcriptase (Anglian Biotec, Colchester, U.K.), 3.5 pmoles of the V L region-specific oligonucleotide primer V K 1F0R [5'-d(GTT AGA TCT CCA GCT TGG TCC C) ] or the V H region-specific primer V H 1F0R-B [5,-d(TGA GGA GAC GGT GAC CGT GGT CCC TTG GCC)], and incubated for 5 minutes at 20*C and then 90 minutes at 42*C.
• Vg BstEII (Vg) restriction enzymes, and cloned into the PvuII and Bell restriction sites of the vector M13V j ⁇ PCR3 (for V L region; Orlandi e£ al, 1989) or the Pstl and BstEII restriction sites of the vector M13V H PCR1 (for V H region) .
• V ⁇ region clones were first screened by hybridisation to a 32 P-labeled oligonucleotide probe [5'-d(GTT TCA TAA TAT TGG AGA CA) ] specific for the CDR2 of the Y3-Ag 1.2.3 V L region.
• V L region clones not hybridising to this probe and V H region clones were sequenced by the dideoxy chain termination method (Sanger et al, PNAS USA 74.: 5463, 1977). Reshaped Light Chain Variable Region and Expression Vector Construct.
• the reshaped light chain was constructed by oligonucleotide-directed in vitro mutagenesis in an M13 vector by priming with three oligonucleotides simultaneously on a 748 base single-stranded cDNA template encoding the entire V L and kappa constant (C ⁇ ) regions of the reshaped CAMPATH-1 antibody (Reichmann et al.. Nature 332: 323-327, 1988).
• the three oligonucleotides [5'-d(AGA GTG ACC ATC ACC TGT CTA GCA AGT GAG GAC ATT TAC AGT GAT TTA GCA TGG TAC CAG AAG CCA) , 5 « -d(CTG CTG ATC TAC AAT ACA GAT ACC TTG CAA AAT GGT GTG CCA AGC AGA TTC) , 5 « -d(ATC GCC ACC TAC TAC TGC CAA CAG TAT AAC AAT TAT CCG TGG ACG TTC GGC CAA GGG ACC) ] were designed to replace each of the three CDRs in the REI-based human antibody V ⁇ region framework that is part of the reshaped CAMPATH-1 antibody V L region (Reichmann et al., 1988) .
• a clone containing each of the three mutant oligonucleotides was identified by nucleotide sequencing and was subcloned into the Hindlll site of the expression vector pH/SAPr-1 (Gunning et al. PNAS, 84.: 4831- 4835, 1987) which also contained a dihydrofolate reductase gene (Ringold et al, J.Mol.Appl. Genet. ! '• 165-175, 1981) driven by a truncated SV40 promoter.
• CD4V H NEW-Thr 3 ° and CD4V H NEW-Ser 30 Two versions of the NEW-based reshaped heavy chain were created, CD4V H NEW-Thr 3 ° and CD4V H NEW-Ser 30 .
• the CD4V H NEW- Thr 30 version ( Figure 6) encodes a threonine residue at position 30 while the CD4V H NEW-Ser 30 version ( Figure 7) encodes a Ser residue at position 30.
• CD4V H NEW-Thr 3 ° was created first by oligonucleotide-directed in vitro mutagenesis in the vector M13mpl8 by priming with three oligonucleotides simultaneously on a 1467 base single-stranded cDNA template ( Figure 5) encoding the entire heavy chain of the reshaped CAMPATH-1 antibody (Reichmann et aJL, 1988) .
• the three oligonucleotides [5'-d(TCT GGC TTC ACC TTC ACC AAC TAT GGC ATG GCC TGG GTG AGA CAG CCA CCT), 5'-d(GGT CTT GAG TGG ATT GGA ACC ATT AGT CAT GAT GGT AGT GAC ACT TAC TTT CGA GAC TCT GTG AAG GGG AGA GTG) ,5'-d(GTC TAT TAT TGT GCA AGA CAA GGC ACT ATA GCT GGT ATA CGT CAC TGG GGT CAA GGC AGC CTC) ] were designed to replace each of the three complementarity determining regions (CDRs) in the NEW-based V H region that is part of the reshaped CAMPATH-1 antibody (Reichmann et al.
• CD4V jj KOL-Thr 113 version encodes a threonine residue at position 113 ( Figure 11) while the CD4V H K0L-Pro 113 version encodes a proline residue at position 113 ( Figure 9) .
• CD4V H KOL-Thr 113 was created first by oligonucleotide-directed in vitro mutagenesis of single- stranded DNA template containing the 817 base Hindlll-BamHI fragment encoding the VJJ region of the rat CD4 antibody ( Figure 4) cloned into M13mpl8 by priming simultaneously with five oligonucleotides [5'-d(CAC TCC CAG GTC CAA CTG GTG GAG TCT GGT GGA GGC GTG GTG CAG CCT GG) , 5'-d(AAG GTC
• CD4Vi j KOL-Pro 113 was created second by oligonucleotide- directed in vitro mutagenesis of single-stranded DNA template containing the 817 base Hindlll-BamHI fragment encoding CD4V H KOL-Thr 113 cloned into M13mpl8 by priming with the oligonucleotide [5'-d(TGG GGC CAA GGG ACC CCC GTC ACC GTC TCC TCA) ] .
• a clone containing this mutant oligonucleotide was identified by nucleotide sequencing.
• the immunoglobulin promoters were removed from the double-stranded DNA forms of clones encoding CD4V jj KOL- Thr 113 ( Figure 11) and CD4V H KOL-Pro 113 ( Figure 9) by replacing (for both versions) the first 125 bp (Hindlll- Ncol) with a Hindlll-Ncol oligonucleotide linker fragment [5'-d(AGC TTT ACA GTT ACT GAG CAC ACA GGA CCT CAC) and its overlapping complement 5'-d(CAT GGT GAG GTC CTG TGT GCT CAG TAA CTG TAA) ] .
• Fluorescence activated cell sorter FACS ⁇ analysis The relative affinities of the reshaped antibodies to bind the CD4 antigen were estimated by FACS analysis.
• the CD4-expressing cells used in this analysis were a cloned rat T cell line NB2-6TG stabily transfected with an expression vector containing a complementary DNA (cDNA) encoding the human CD4 antigen (Maddon et al, Cell, 42., 93- 104, 1985). Cells were stained with the appropriate reshaped antibody followed by fluorescein-conjugated sheep anti-human antibodies (Binding Site Ltd., Birmingham, UK). Control staining (see Table 1) consisted of no antibody present during the first stage of cell staining. Mean cellular fluorescence was determined with an Ortho FACS.
• the relative avidities of the rat YNB46.1.8 antibody and the reshaped CD4V H KOL-Thr 113 antibody were estimated by an enzyme-linked immunosorbent assay (ELISA) .
• ELISA enzyme-linked immunosorbent assay
• Microtiter plates were coated with soluble recombinant CD4 antigen (Byrn et al. Nature, i: 667-670, 1990) at 50 ul/well, 10 ug/ml, and then blocked with 100 ul/well phosphate buffered saline (PBS) containing 1.0% bovine serum albumin (BSA).
• PBS phosphate buffered saline
• BSA bovine serum albumin
• Antibodies were diluted in PBS containing 0.1% BSA, and added to wells (50 ul/well) for 45 minutes at room temperature.
• Biotinylated CD4V H KOL-Thr 113 antibody (10 ul/well; 20 ug/ml final concentration) was then added to each well for an additional 45 minutes. Wells were washed with PBS containing 0.1% BSA, and then 50 ul streptavidin- biotinylated horseradish peroxidase complex (Amersham; Aylesbury / UK) diluted 1:1,000 was added to each well for 30 minutes.
• V__. and VJJ regions from CD4 antibody- secreting hybridoma cells were isolated by PCR using primers which amplify the segment of mRNA encoding the N- terminal region through to the J region (Orlandi et al. 1989) .
• V L and V H region PCR products were subcloned into the M13-based vectors M13V K PCR3 and M13V H PCR1, respectively.
• the CD4 antibody ' V H region to contain the V H region framework sequences of the human antibody KOL.
• the overall amino acid sequence of the V H region of KOL is most homologous to the rat CD4 antibody V region.
• the V H regions of the human antibodies KOL and NEW are 66% and 42% homologous to the rat CD4 antibody VJJ region, respectively.
• CD4V j KOL-Pro 113 ( Figure 10) encodes a proline residue at position 113 and CD4V H KOL-Thr 113 ( Figure 12) encodes a threonine residue at position 113.
• CD4V j KOL-Pro 113 is "true to form" in that its framework sequences are identical to those of the KOL antibody heavy chain V region ( Figure 8) .
• NEW-based reshaped CD4 antibody heavy chains CD4V j NEW-Thr 3 ° and CD4V NEW-Ser 30 , is also expressed with the KOL-based reshaped CD4 antibody heavy chains CD4V H KOL-Pro 113 and CD4V KOL-Thr 113 . This is advantageous because expression of the same reshaped light chain with different reshaped heavy chains allows for a direct functional comparison of each reshaped heavy chain.
• the reshaped light chain of each antibody is called CD4VLREI.
• the reshaped heavy chains of the antibodies are called CD4V H NEW-Thr 30 , CD4V jj NEW-Ser 30 , CD4V H KOL-Pro 113 , and CD4V H KOL-Thr 113 , respectively.
• Each of the reshaped heavy chains contain the same human IgGl constant region.
• the name of a reshaped antibody's heavy chain shall be used below to refer to the whole antibody (heavy and light chain combination) .
• CD4V H KOL-Thr 113 antibody binds CD4 + cells with far greater affinity than CD4VjNEW-Thr 30 antibody.
• the lowest concentration of CD4V KOL-Thr 113 antibody tested (2.5 ug/ml) gave a mean cellular fluorescence nearly equivalent to that of the highest concentration of CD4V NEW-Thr 30 antibody tested (168 ug/ml) .
• Experiment 2 demonstrates that CD4Vj j NEW-Ser 30 antibody may bind CD4 + cells somewhat better than CD4VJJNEW- Thr 30 . Only 2.5 ug/ml CD4V H NEW-Ser 30 antibody is required to give a mean cellular fluorescence nearly equivalent to 10 ug/ml CD4V j NEW-Thr 30 antibody.
• CD4V H KOL-Thr 113 antibody may bind CD4 + cells somewhat better than CD4V H KOL-Pro 113 antibody. From these assays, it is clear that the KOL-based reshaped antibodies are far superior to the NEW-based reshaped antibodies with regards to affinity towards CD4 + cells. Also, there is a lesser difference, if any, between CD4V H NEW-Thr 30 antibody and CD4V H NEW-Ser 30 antibody, and likewise between CD4V KOL-Thr 113 antibody and CD4V j KOL- Pro 113 antibody.
• a ranking of these reshaped antibodies can thus be derived based on their relative affinities for CD4+ cells: C__4V H DI Jackpot 113 > CD4VjKDI_-Pro 113 » ⁇ MV j ⁇ EW-Ser 30 > - ⁇ WV j ⁇ -SW- r 30
• each of the reshaped CD4 antibodies used in the above experiments have the identical heavy chain constant regions, and are associated with identical reshaped light chains. Thus observed differences of binding to CD4+ cells must be due to differences in their heavy chain V regions.
• the relative avidities of the rat YNB46.1.8 antibody and the reshaped CD4VjKOL-Thr 113 antibody were estimated by ELISA. In this assay, the ability of each antibody to inhibit the binding of biotinylated CD4V H KOL-Thr 113 antibody to soluble recombinant CD4 antigen was determined. Results of an experiment are shown in Figure 13.
• the inhibition of binding of biotinylated CD4V KOL-Thr 113 antibody was linear for both the unlabeled CD4V KOL-Thr 113 and YNB46.1.8 antibodies near the optical density of 0.3.
• the concentrations of CD4V H KOL-Thr 113 and YNB46.1.8 antibodies that give an optical density of 0.3 are 28.7 and 1.56 ug/ml, respectively.
• YNB46.1.8 antibody can be estimated to be 28.7/1.56 or about 18 times better than that of CD4V H KOL-Thr 113 antibody. It should be noted that this experiment only provides a rough approximation of relative avidities, not affinities.
• the rat YNB46.1.8 antibody contains a different constant region than that of the CD4V KOL-Thr 113 antibody, and this could affect how well the antibodies bind CD4 antigen, irrespective of their actual affinities for CD4 antigen.
• the actual affinity of the reshaped antibodies for CD4 antigen may be greater, lesser, or the same as the YNB46.1.8 antibody.
• the other reshaped antibodies CD4V H K0L-Pro 113 , CD4V H NEW-Ser 3 °, and CD4V H NEW- Thr 30 have not yet been tested in this assay.
• CD4V H KOL-Pro 113 100 594.9 CD4V H KOL-Pro 113 40 372.0 CD4V H KOL-Pro 113 10 137.7 CD4V jj KOL-Pro 113 2.5 48.9 CD4V H KOL-Thr 113 100 696.7 CD4V H KOL-Thr 113 40 631.5 CD4VjKOL-Thr 113 10 304.1 CD4V H KOL-Thr 113 2.5 104.0

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